This invention relates in general to a mechanism for generating a pulse by switching the state of a magnetic device that has come to be known as a Wiegand wire and more particularly to a mechanism and method for affecting the magnetic field to which a Wiegand wire module is subjected so as to provide a reliable and repeatable output pulse upon the occurrence of a predetermined event.
The magnetic device employed in the pulser of this invention is of the type disclosed in U.S. Pat. No. 3,820,090 issued June 25, 1974. A preferred embodiment of this magnetic device is disclosed in U.S. Pat. No. 4,247,601 issued Jan. 27, 1981 to John R. Wiegand and entitled "Switchable Magnetic Device and Method of Manufacturing Same". These magnetic devices are ferro-magnetic wire segments which have been treated in such a fashion as to provide core and shell portions with divergent magnetic properties. This type of wire has come to be known in the art as Wiegand wire.
The Wiegand wire essentially has two states. In one of these states, the magnetization of the core and shell are in opposite directions and this state may conveniently be called a reverse state. In the other state, the magnetization of the core and shell are in the same direction and this state may conveniently be called the confluent state. When the magnetic field to which the wire is subjected passes a threshold in one direction or the other, the wire switches state. The switch in state is extremely rapid so that the rate of change of flux through a pickup coil wrapped around the wire is great. As a consequence the output from the pickup coil is very substantial, in some cases being as high as eight volts into an open circuit on a repeatable basis. The wire and pickup coil is referred to as a module.
The characteristics of a pulse generator which are desirable include simplicity, low cost, versatility, repeatability, reliability and high output pulse. There are inevitably certain trade-offs in enhancing certain of these characteristics at the expense of other characteristics. However, it is desirable to provide an optimum combination of these characteristics with whatever enhancement of the characteristics may be achieved to improve design and such is the general purpose of this invention.
More particularly, this invention is directed to the providing of a switching magnetic field configuration that has been found to enhance the magnitude of the output signal provided in a pick-up coil wrapped around the Wiegand wire. This invention is also directed to achieve this result by means of a simple motive arrangement that avoids complex mechanisms.